你会学到什么：
- Implementing bidirectional power conversion in a solar installation.
- WBG材料如何在高压功率转换中发挥关键作用。
- Developing higher-accuracy voltage and current sensing/monitoring.
虽然光伏（PV）太阳能装置继续加速，但太阳电网供需边的不平衡被出现为一个主要限制。当需求不高时，太阳能大量可用，这意味着消费者在早上和晚上的峰值使用率期间每瓦的价格较高。
用于住宅，商业和实用太阳能装置的能量储存系统（ESS）使逆变器能够在需求最低的情况下储存白天收集的能量或从网格中拉动电源，当需求高时提供这种存储的能量。通过向太阳网连接系统添加ESS，用户可以通过称为“峰值剃须”的练习来降低成本。
在本文中，我将探讨网格连接的存储集成太阳能安装系统中的设计考虑因素。
Bidirectional Power Conversion
Conventional solar installations comprise unidirectional dc-ac and dc-dc power stages, but a unidirectional approach presents a major barrier to ESS integration. It requires more components, modules, and subsystems, all of which significantly raise the cost of incorporating an ESS to an existing solar installation.
将存储添加到现有的太阳能安装需要将两个路径组合到电池充电和将电池放电到包括功率因数校正（PFC）和逆变电源级的单个路径。但是如何构建双向电源转换器以替换两个单向电源转换器？
高级双向功率拓扑显示在Figure 1enable the safe, efficient transfer of power between the grid, PV array, and battery-management system. Microcontrollers (MCUs) such asC2000.real-time MCUs are popular for such power topologies. These controllers can each control one or multiple power stages to enable a digitally controlled, bidirectional power-conversion architecture for an ESS-enabled solar inverter. MCU-enabled control facilitates more sophisticated pulse-width-modulation (PWM) schemes for the power switches handling the dc-ac and dc-dc conversions.
混合逆变器有助于转换阶段实现更高的效率，这在ESS集成的微电网中变得更加重要，因为发生了多种电源转换。Power-Converter Systems处理DC-DC操作以充电和放电电池，以及DC-AC和AC-DC操作，将存储在电池中的直流电源转换为AC以将其送入网格并返回。
Higher-Voltage Batteries
在存储集成的MicroGrid系统中，电池的主要功能是在提示时将PV能量存储到网格中。锂离子电池组每单位提供比铅酸电池更高的电荷储存能力。
在电动车（EV）段中，400 V电池组流行，还可以推动超出48 V电池组的太阳能电网安装中的电池电压。但是如何管理400 V电池组的电源转换？
Along with MCUs that provide system control and communication to help ESSs integrate into larger systems, power switches with low losses and high efficiency also make energy-storage systems safe and reliable. Compact power switches based on silicon-carbide (SiC) and gallium-nitride (GaN) materials, along with real-time control MCUs, help ensure the adaptation of a bidirectional converter so that it can operate with various dc energy-storage units（图2）。
Wide-bandgap (WBG) semiconductors such as SiC and GaN will play an important role in addressing power-conversion systems that can handle increased battery-voltage ranges given the converter’s higher power density and lower switching losses. Power-conversion systems also help battery packs better manage power fluctuations in distributed generation systems, and make grid operations smart and resilient at higher and wider voltage ranges.
Eventually, solar installations might mimic the battery packs used in EVs. There’s a growing belief that the battery packs currently used in EVs will be recycled for a second life as a grid-connected ESS.
WBG Materials for Efficiency and Natural Convection
To create a sleek wall-mounted storage system, you must ensure that the inverter design is thermally optimized with minimal natural convection cooling. A分布式电力架构can spread the concentration of heat throughout the system. Such architectures also enable the energy-storage inverter needed to support high current levels at different voltages, and to provide a reliable transient response to rapidly changing loads.
Such a system will require gate drivers that can support fast switching and provide protection at switching frequencies from 100 to 400 kHz. If switching isn’t fast enough, power-conversion stages can suffer huge efficiency losses.
That’s where WBG materials such as SiC and GaN come into play, offering faster switching and higher power density. These semiconductor devices facilitate design systems that don’t require fan-based cooling. The LMG3425R030, a GaN device with integrated driver and protection features, provides a compact form factor, higher power density, and faster switching capabilities.
这gate driver translates the digital PWM signal from the controller to the current required by the SiC or GaN field-effect transistor. The PWM-based controllers ensure that voltages and currents are accurately sampled at multiple power-conversation stages.
这Bidirectional High-Density GaN CCM Totem Pole PFC Using C2000 MCU参考设计包括双向图腾杆无桥PFC功率级，采用C2000实时MCU和LMG3410R070GaN FET with integrated driver and protection(Fig. 3)。这3-kW bidirectional design supports phase shedding and adaptive dead time for efficiency improvements, and a nonlinear voltage loop to reduce voltage spikes during transients in PFC mode.
电流和电压传感
权力design switching at high frequencies includes the challenge of accurate current and voltage sensing. Shunt-based current measurements aren’t only more accurate, but they also offer faster response times to react quickly to any change in the grid, shutting off the system in case of a short circuit or grid connection loss.
Current measurements are an inherent part of inverter-centric designs because control algorithms require current sensing for control purposes. Design solutions are available for isolated current measurements using external shunts and isolated amplifiers or modulators and power supplies. For example, the三级三相SIC AC-TO-DC转换器参考设计employs theAMC1306孤立的调制器用于负载电流监控。AMC3306是一个具有集成DC-DC转换器的下一代隔离调制器，可实现一次性供电。
For any digital signals that need to transfer data across various voltage domains in inverter-driven applications using higher voltages, isolation devices could be used to overcome voltage limitations. Digital isolators such as theISO7741enable high-frequency signals to cross power boundaries, while protecting low-voltage digital circuits from the high-voltage domain.
功率转换器必须测量网格电流以确保电流与电压相位相位。电流和电压测量还控制电池充电电流以及逆变器操作和过载保护。
Conclusion
提供双向AC-DC和DC-DC电源转换的混合逆变器可能会在几年内取代传统的太阳能逆变器。混合逆变器允许太阳能逆变器设计人员利用各种输出功率和电压来实现电源转换。
对于能够存储的太阳能逆变器，更高和更宽的电池电压范围物质。随着对高效率和自然对流的需求，基本构建块如MCU的控制和具有集成栅极驱动器和保护功能的WBG半导体可以适应这些更高且更宽的电池电压范围。
C2000实时单片机和LMG3425R030 GaN设备re able to handle bidirectional energy transport in a storage-capable solar grid. Likewise, shunt-based current and voltage sensing can ensure that higher voltage batteries and fast switching power converters work safely and reliably.
